This research project is directed toward study of the metabolism of micro-nutrients, particularly vitamin B12 and folate, in terms of their absorption, transport, utilization, fate and excretion. In addition, the proteins which bind the micronutrients are studied, both in terms of their own synthesis and degradation and in their effect on the micronutrients concerned. A major emphasis of the project is the development and improvement of assay for the nutrients and their binding proteins.